Liquid return for intermittent absorption refrigerators



June 20, 1933. T. B. FOCKE 1,914,687

uouni RETURN FOR INTERMITTENT ABSORPTION REFRIGERATORS Filed Aug. 7,1951 3 Sheets-Sheet 1 June 29, 1933. T B, FQCKE $14 6 87 LIQUID RETURNFOR INTERMITTENT ABSORPTION REFRIGERATORS Filed Aug. 7, 1931 3Sheets-Sheet 2 June 20, 1933. 1-. B. FOCKE 1,914,687

LIQUID RETURN FOR INEERMITTENT ABSORPTION REFRIGERATORS Filed Aug. 7,1931 3 Sheets-Sheet :s

Patented June 20, 1933 UNITED STATES PATENT OFFICE THEODORE B. FOCKE, OFCLEVELAND HEIGHTS, OHIO, ASSIGNOR TO PERFECTION STOVE COMPANY, OFCLEVELAND, OHIO, A COBPORATION OF OHIO LIQUID RETURN FOR INTERMITTENTABSORPTION REFRIGERATORS Application filed August 7, 1931. Serial No.555,771.

This invention relates to intermittent absorption refrigerators which,as is generally known, consist of a generator-absorber and areceiver-evaporator that are connected to gether by conduits, one ofwhich has associated with it a condenser, the whole constituting ahermetically sealed system that contains a quantity of suitablerefrigerant and a quantity of absorbent therefor, in proper proportions.The refrigerant may consist of ammonia, for example, and the absorbent,watefl and a suitable heating device is arranged in operative relationto the generatorabsorber.

In the operation of the apparatus, when the heating device is effective,the mixture in the generator-absorber boils and the refrigerant vaporspass to the condenser and the resultant anhydrous refrigerant liquid isconducted to the receiver-evaporator. This portion of the operation,known as the heating phase, continues until the required amount ofrefrigerant is distilled over into the receiverevaporator; and theheating of the generatorabsorber is then discontinued. Thereupon Y thepressure, which has risen to a considerable valueduring the heatingperiod, falls, and the refrigerant in the receiver-evaporator evaporatesand passes back in the form of gas to the generator-absorber to beabsorbed by the weak liquor in the latter vessel.

Although a dehydrator is usually provided between the generator-absorberand the con denser for recovering absorbent vapors,

which pass with the refrigerant vapors from the generator-absorber, andcondensing and returning them to the generator-absorber, it invariablyhappens that a certain amount of the absorbent is distilled over withthe refrigerant into the receiver-evaporator; and if this were notremoved at frequent intervals it would accumulate and soon materiallyreduce the efiiciency of the apparatus. 0 It is the purpose of theinvention to provide simple, efiicient, and thoroughly reliable meansfor returning absorbent liquid that has accumulated in thereceiver-evaporator during a heating period to the generatorabsorberbefore the next cycle of operation.

0 A further object is to provide means of this character that willfunction regardless of the relative elevated positions of thegeneratorabsorber and the receiver-evaporator. By virtue of certainembodiments of my invention, the generator-absorber may be at a higheror lower plane than the receiver-evaporator or in a common planetherewith.

Various embodiments of the invention are illustrated in the accompanyingdrawings,

frigerator incorporating my improved liquid return means; Fig. 2 is asimilar View showmg a modification of the liquid return means, and Fig.3 is a diagram of refrigeration apparatus incorporating a form of myliquid return means applicable only to a situation in which thegenerator-absorber is at a lower level than the receiver-evaporator.

Throughout the views, 1 designates the generator-absorber and 2 thereceiver-evaporator. A vapor delivery conduit 3 leads from the upperportionof the generator-absorber to the lower portion of thereceiver-evaporator, and, according to the present illustrativeembodiment, a part of the conduit is in the form of a coil 3- which,with a tank 4 wherein it is enclosed, constitutes a condenser. The tank4 contains a suitable quantityof cooling liquid, and the portion of theconduit 3, between the vertical branch that rises from thegenerator-absorber and where said conduit merges into the coil 3 isinclined upwardly toward the coil to provide a dehydrator desig; nated3. A heating device 5, shown conven tionally as a gas burner, is locatedbelow and in operative relation to the generator-absorber -1.

Considering now the embodiment illustrated in Fig. 1, a gas returnconduit 6 leads from the receiver-evaporator to the generator-absorber,and, in the latter vessel,it extends downwardly to a point below theminimum liquid level therein, while its opposite or receiving end dipsinto the receiver-evaporator to a point somewhat below the normalmaximum liquid level in the last mentioned vessel, such level beingindicated by the line x. A liquid return tube or conduit 7 extends fromvery near the bottom of the receiverevaporator upwardly through the topof said vessel and thence laterally and upwardly and joins the conduit(3 a short distance above the generator-absorber 1.

When the heating device 5 is in operation, the mixture of absorbent andrefrigerant in the generator-absorber 1 boils and the vapors v thereofrise through the conduit 3, all or the greater part of the absorbentvapors condensing within the dehydrator portion 3 of the conduit andreturning by gravity to the generator-absorber. The refrigerant vaporsand such of the absorbent vapors as may have passed the dehydratorcondense in the coil 3 and from there gravitate into thereceiverevaporator 2, accumulating therein until the liquid level isapproximately at the height indicated by the line a, at which time theheating device is rendered ineffective in any suitable way. During thisheating period the pressure within the system rises to a relatively highvalue, and when the heat is discontinued the pressure within the systemand especially within the generator-absorber 1 immediately starts tofall and thus creates a differential in the pressures prevailing in thegenerator-absorber and the receiver-evaporator, that in the formervessel abviously being the lower. Under the influence of the higherpressure in the receiver-evaporator, the liquid level therein is loweredand the displaced liquid rises within the conduits 3, 6 and 7. Inasmuchas the absorbent present in the receiver-evaporator is heavier than therefrigerant liquid it will collect within the bottom of the vessel andrise through the con duit 7. This action continues until the liquidlevel in the receiver-evaporator fallsbelow the inlet end of the conduit6. Before this condition is reached, however, practically all of theabsorbent liquid has been forced up into the conduit 7 to thedischarging end of the conduit 6 and flows therethrough into thegenerator-absorber. When the receiving end of the conduit 6 becomesuncovered the liquid will recede from said conduit and the refrigerantgas will flow through it and will relieve the pressure sufficiently toprevent further liquid being forced into the conduit 7 and any liquidreposing within said conduit when this occurs will gravitate to thereceiver-evaporator. It is essential that the conduit 6, or a partthereof, be at a materially higher elevation than the highest part ofthe conduit 7, firstly, because the return of the absorbent liquidshould be effected before the refrigerant liquid reaches the highestpoint of the conduit 6 as otherwise it would pass such point and flowinto the generator-absorber; and secondly, because the absorbent liquidis of greater specific gravity than the refrigerant liquid andconsequently would maintain a lower elevation in the conduit'7 than therefrigerant liquid would in the conduit 6, under substantially the samepropelling pressure.

Thus it will be seen that my invention provides a liquid return meansfor intermittent absorption refrigeration apparatus that effectivelyfulfills the purpose hereinbefore set forth.

The modification illustrated in Fig. 2 differs from that above describedonly in this: that the discharge end of the liquid return tube 7 opensinto the top of the generatorabsorber 1 instead of joining the gasreturn conduit 6 or extending to a point below the liquid level in saidvessel. The operation of this form of the invention will be readilyunderstood from the foregoing description of the first form.

In the modification illustrated in Fig. 3, the generator-absorber 1 isbelow the plane of the receiver-ewiporator 2, and a single conduit 7"serves to return both absorbent liquid and refrigerant gas from thereceivercvaporator to the generator-absorber, the con duit having adownwardly directed branch 7 that opens adjacent the bottom of the re-(-eiYer-evaporator, and a branch 6 that rises from the conduit 7 and isdirected over and downwardly into the receiver-evaporator where itterminates a suitable distance below the maximum liquid level in saidvessel.

In considering the operation of this form of the invention, which issubstantially the same as that of the previously described embodiments,it may be explained that as the refrigerant condensate enters thereceiverevaporator through the delivery conduit 3 the liquid will risein the tube 7, the absorbent liquid rising first within the said tubebecause of its natural position about the open end thereof. Therefore,by the time the heating period ceases and the maximum amount ofrefrigerant has been distilled over into the receiver evaporator, theliquid level in the branch 6 will stand at substantially the same heightas the liquid in the receiverevaporator while that in branch 7 will besomewhat lower due o its containing the heavier absorbent liquid; thenwhen the cooling phase begins and the pressure within thereceiver-evaporator forces the liquid upwardly into the branches 7 and6*, that from the branch 7 will flow through the conduit 7" back to thegenerator-absorber 1 before the liquid in the branch 6 reaches thehighest point of said branch. By the time the liquid closely approachesthe high point of the last mentioned branch, the receiving end of saidbranch will have been uncovered by liquid and as a consequence thereofthe pressure in the two ends of the system will equalize and the flow ofliquid through the branch 7 will cease. Thereafter, the refrigerant gasduit 7 to the generator-absorber where it liquid from flowing throughthe gas return will be reabsorbed by the liquor therein.

I am aware that attempts of a nature somewhat similar to that of thepresent invention have been made in the past, as evidenced by I LettersPatent toLunburg No. 1,7 79,070 and mittent absorption type,

to Loetscher No. 1,222,642; but certain differences resulting in markedadvantages distinguish my invention from its predecessors. Having thusdescribed my invention, what I claim is:

1. In refrigeration apparatus of the intercommunicative means leadingfrom the receiver-e-vapora-tor to the generator absorber, said meansinvolving two conduits, one that leads from anabsorbent liquidcollecting portion of the receiver-evaporator and the other having afullopen receiving end sealed by a body of liquid in thereceiver-evaporator when such body is of sulficient volume to fill thereceiver-evaporator to a level at or slightly below normal maximum, saidother conduit having a portion appreciably higher than any part of theformer conduit, the means functioning automatically to return liquidfrom the receiverevaporator to the generator-absorber due to differencein pressure in the two vessels at the commencement of the coolingperiod, said other conduit when the liquid seal is broken serving tocause an approximate equalization of pressure in the two vessels and byreason of its higher position having capacity to receive liquid withoutits overflowing to. the generator-absorber while a flow of liquid isinduced by pressure through the first mentioned conduit. I

2. In refrigeration apparatus of the intermittent absorption type, meansleading from the generator-absorber to the receiver-evaporator, saidmeans involving two conduits, one that leads from an absorbent liquidcollecting portion of the receiver-evaporator, and the other from apoint a relatively short distance below the normal maximum level of abody of liquid nearly filling said vessel, the latter conduit having apart sufiiciently higher than the next highest part of the communicativemeans to prevent liquid from flowing through said latter conduit.

3. In refrigeration apparatus of the intermittent absorption type, a gasreturn conduit leading from a point a relatively short distance belowthe normal maximum level of a body of liquid nearly filling thereceiverevaporator to a point below the minimum liquid level in thegenerator-absorber, and a communicative ing two open end branches, oneextending to the lowest point of the receiver evaporator, the otherbranch extending to a point just below the normal maximum level of abody of liquid nearly filling the receiver-evapo-- rator, the highestpoint of said second branch being sufliciently above any other part ofthe said conduit to prevent liquid from flowing through said secondbranch.

5. In refrigeration apparatus of the intermittent absorption type, anunobstructed gas return conduit having its receiving end full open at apoint just below the normal maximum liquid level in thereceiver-evaporator, said conduit extending therefrom to a point belowthe minimum liquid level in the generator-absorber, a liquid returnconduit extending from the lowest point in the receiverevaporator to apoint above the highest liquid level in the generator-absorber, thehighest point of said gas return conduit being sufliciently above thehighest point of said liquid return conduit to prevent liquid fromfiowing through the gas return conduit.

6. In refrigeration apparatus of the intermittent absorption type, aconduit for returning liquid from an absorbent liquid collecting portionof the receiver-evaporator to the generator-absorber due to difi'erencesin pressure in the two vessels at the commencement of a cooling period,and an unobstructed gas return conduit leading from the rethe firstmentioned conduit to prevent liquid from flowing through the gas returnconduit.

7. In refrigeration apparatus of theintermittent absorption type whereinthe generator-absorber is situated at a lower level than thereceiver-evaporator, a conduit leading from an absorbent liquidcollecting portion of the receiver-evaporator upwardly above the maximumliquid level in said vessel and thence to a point below the minimumliquid level in the generator-absorber, and a branch conduit leadingfrom the first mentioned conduit above the maximum liquid level in thereceiver-evaporator upwardly a suitable distance and thence downwardlyinto the receiver-evaporator to a point a relatively short distancebelow said maximum liquid level. V

8. In refrigeration apparatus of the intermittent absorption type, a gasreturn conduit leading from a point a relatively short distance belowthe normal maximum liquid level in the receiver-evaporator to a pointbelow the minimum liquid level in the generatorabsorber, and a liquidreturn conduit leading from an absorbent liquid collecting portion ofthe receiver-evaporator and joining the gas return conduit before thelatter enters the generator-absorber, the highest part of the gas returnconduit being above the normal maximum liquid level in thereceiverevaporator an amount equal to or greater than the verticaldistance between the highest part of the liquid return conduit and thenormal maximum liquid level in the receiverevaporator times the ratio ofthe specific gravities of the liquids at the absorbent liquid collectingportion of the receiverevaporator and the liquid at the normal maximumlevel in the receiver-evaporator, respectively.

In testimony whereof, I hereunto afiix my signature.

THEODORE B. FOCKE.

